Hahahah actually I was saying to splice the wall wart wires to conect 2 power boards (would that be considered parallel? 
idk) but considering that I donāt have a tester to actually know how much each board is drawing Iāll consider geting one before taking action to avoid major catastrophes. 
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yeah better safe than sorry . under powered modules can be a pain in the ass to trouble shoot because it can seem like something is wrong with the components / build on your modules when its just not enough power going into them .
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So a little update on the matter I got a multimeter, but it turns out itās not as simple as I initially thought.
If I want to measure the current drawn by a module should I connect the +12 output from the power board to the input of the module, do the same with the -12 and add up the values together?
Also, does it matter if the moduleās ouput is plugged or not?
Theyāre separate supply rails so adding the currents doesnāt really make sense, at least not if youāre trying to figure out if you have enough power. If you click over to e.g. www.modulargrid.net youāll see that they report the current separately for +12, ā12, and +5.
(you can sum +12/ā12 if you want to calculate the total power consumption in watts, but that wonāt help you with the power supply issue, since the current consumption needs to be within the limits for each individual output.)
(Also a tip if youāre new to measuring current with multimeters: make sure to always move the leads back to voltage immediately after youāre done measuring. If you donāt, you will invariably forget to do that later, and blow the fuses next time you try to measure a voltage. If you have 10 ohm resistors on the module rails, itās safer to measure the voltage drop over the resistors than using the multimeterās current mode.)
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Depends on the module. Most will probably use a bit more current if theyāre connected to something else, but that may be negligible.
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And if you donāt you can make one of these:
(Two 10-pin power headers and two 16-pin power headers all connected, with 10R resistors in series on the Ā±12 V and +5 V rails, and a pair of pin headers, with pins on the ground strips removed, as test points. Plug in cable to power supply on one side, cable to module on other side, measure voltage from one pin header to the other, divide by 10.)
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So it means that if a module is drawing (even if itās a crazy value) 1A on each rail Iām okay to power it with a 12vAC 1A? (Also giving some headroom)
Thanks a lot for the tips! Mine is forced to choose manually after turning off but that way I can compare the results after being sure Iāve setted it right! ^^
You need to look at supply inputs and outputs separately ā if a supply is to provide 1 A on each rail, it needs more than double that in, but that doesnāt mean that you can power a module that uses 1.5 A on one rail and 0.5 A on the other from the same supply, even if the wattage is the same. If your supply is symmetrical, like a wall-wart style supply is (each DC rail is powered by one half of the input AC), the input current is proportional to 2ĆMAX(rails), not SUM(rails).
Mine is forced to choose manually after turning off
If you donāt have to move the leads to measure current, youāre probably safe (but probably cannot measure a lot of current, or the multimeter is really dangerous since that means you can switch from very high impedance to a short-circuiting very low impedance by mistake, without moving the leads).
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I do have a +12/-12 power supply powered by a 1A AC wall-wart, that means that each rail is getting Ā±500mA?
I mean, would this be equal to the total Amps given by the wall wart? :
Iām sorry, Iām having a little hard time getting this and Iām not sure if Iām pointing my questions correctly.
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Yes thatās it 
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Ok, letās try again, from the power supply side this time
The wall-wart supply uses the positive half of the AC input to power the +12 V rail and the negative half to power the ā12 V rail. Half the input power goes to each rail, which gives you half the input current on each side.
(this is called half wave rectification, and the wall wart supply is basically two such rectifiers, using one of the AC inputs as a common 0 V).
If you find that your modules use e.g. a total of 800 mA on +12 V and 200 mA on ā12 V, you need to make sure the power supply can provide both these currents. Since the supply is symmetrical, each rail using half the input power, you need to dimension the input for 2Ć the largest of 800 mA and 200 mA, i.e. 2Ć800 mA = 1.6 A.
If youād added the currents instead and used that to dimension the supply input, youād gotten 1000 mA or 1 A, but 1 A in is not enough to provide 800 mA for +12 V once the input has been split in half.
(You also need to add a bit of margin here, since some power will get lost on the way, and most of that loss will heat up the regulators. The more milliamperes you pull out of the supply, the more important it gets that you have large enough heatsinks.)
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As clear as water!
I think I got confused by that before, wasnāt sure in which direction we were talking and that kinda changes thing a lot 
I really appreciate you started from the begining, thank you! ^^
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Iām building FC-power from FrequenceControl. The BOM refers to 7812/7912 for voltage regulation, each with a max output current of 1.5 A (pdf specs).
Iām using a 5A AC PSU, so I wonder if I could also use 78S12 series (pdf specs), which have a max output current of 2 A.
Do you have experience with proper heatsinks for 2 A?
Hereās a picture if mine.
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Trying this on the next case. Sick of dealing with wall warts.
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Iām having to rethink my power situation. Iāve got enough modules now that itās an issue. Iāve been using a wall wart along with AI Synthesis power supply and bus boards. The bus boards are fine, but I donāt consider warts and the supply board a very scalable solution. Iāve thought about moving to a pair of beefier (5A+) switching supplies, but Iām worried about ripple and heat dissipation if I add in rail regulators. Is there a consensus view on throwing in a pair of switching supplies and feeding them straight into bus boards, or should I try to condition the outputs? The supplies Iām looking at list 120mv p-p ripple on the data sheet, which seems iffy. I could pop on some goodly sized bypass caps and regulators, but I worry about current draw through the regulators. Any thoughts?
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People certainly have done it, without regulators, e.g. here
but I donāt know how problematic the ripple is for them.
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Yeah, I saw that post and am looking at that very pair of Mean Wells. I was a little surprised to see those outputs pumped straight into the bus - hence my question about ripple.
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I havenāt watched this yet but I bet itās worth doing so:
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@lookmumnocomputer Would I need bigger heat sinks for the Frequency central power supplies to handle the 3amps? im running 2amps on one as im still waiting for the other and it gets toasty warm!ou seem the guy to ask a I followed your diy power supply tutorial but the link is dead for the power brick you recomended
@ehisforadam did not have success with the nozoĆÆd design.
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